1. Field of the Invention
The present invention relates to a hybrid hotair heater in which a plurality of heating means are incorporated in one frame.
2. Description of the Related Art
Jpn. Pat. Appln. KOKAI Publication No. 2000-9347, for example, describes a hybrid hotair heater in which a combustion heater portion and an electric heater portion are incorporated in a frame and one air blowing fan constitutes an air blowing system. In this case, if the air blowing system is controlled by the one air blowing fan, a quantity of generated heat is different between a case where the electric heater portion is used for heating in addition to the combustion heater portion and a case where only the combustion heater portion is used for heating while the electric heater portion is at rest, so that to prevent overheating it is necessary to make different a quantity of air to be sucked in the frame between these two cases, thus making it difficult to operate the combustion heater stably because of a difference in quantity of combustion air.
Therefore, is may be considered to arrange the combustion heater and the electric heater one above the other in such a configuration that the air blowing fan as well as an inlet and an outlet may be provided for each of them to thereby make the respective air blowing systems independent of each other. In this case, the outlets and the inlets are provided adjacent to each other in, for example, a front face and a rear face of an appliance respectively.
It is to be noted that in a case where a hybrid hotair heater is arranged as described above to provide an inlet in a combustion heater portion and that in an electric heater portion adjacent to each other, if only a combustion heater portion is operated for heating, as air around the inlet in this combustion heater is sucked in a frame, the air may in some cases flow back from an outlet in the electric heater portion to the inlet through an air blowing passage.
In such a case, dust around the outlet is sucked in the air blowing passage of the electric heater portion and sticks to the electric heater provided in this air blowing passage. If the electric heater is operated in this condition, the dust is heated to burn, so that nasty smell occurs when heating starts, which is a problem. In this case, a filter is mounted over the inlet, but it is not desirable to mount a filter over the outlet of which hotair is blasted out, because the filter provides resistance against the hotair.
In view of the above, it is an object of the present invention to provide a hybrid hotair heater that can prevent offensive smell from occurring when heating starts by use of an electric heater.